Energy-efficient systems including mechanical vapor compression for biofuel or biochemical plants

ABSTRACT

Processes and systems are provided to compress vapors produced in distillation and recover the heat of condensation through mechanical vapor compression and to derive mechanical and electrical energy from a combined heat and power system, while maintaining the plant&#39;s original ability to operate. The plant&#39;s existing distillation system, steam generation, and electrical demand determine the design basis for the retrofit system that is targeted at an optimized combination of energy usage, energy cost, and environmental impact. Mechanical vapor compression minimizes the total energy usage. Combined heat and power provides a means of converting energy between fuel, electricity, and thermal energy in a manner that best complements plant requirements and energy economics and minimizes inefficiencies and energy losses.

PRIORITY DATA

This patent application is a continuation application of U.S. patentapplication Ser. No. 15/453,881, filed on Mar. 8, 2017, which claimspriority to U.S. Provisional Patent App. No. 62/314,358, filed on Mar.28, 2016; U.S. Provisional Patent App. No. 62/330,847, filed on May 3,2016; and U.S. Provisional Patent App. No. 62/414,165, filed on Oct. 28,2016, each of which is hereby incorporated by reference herein.

FIELD OF THE INVENTION

The present invention generally relates to processes, systems, andapparatus for recovery and refinement of bio-products frombio-fermentation plants requiring distillation.

BACKGROUND OF THE INVENTION

The process energy consumed in the distillation of bio-products oftenconstitutes the largest energy requirement in the production life cycleof those products. Distillation systems are designed to meet a number ofrequirements appropriate to the priorities existing when design andinvestment decisions are made. First-generation distillation systemswere implemented when simplicity was highly prized and environmentalconcerns related to energy usage were largely relegated to minimizingassociated hazardous emissions. Today, policies and regulatoryinitiatives targeting the reduction of greenhouse gas emissions areimpacting consumers and producers of energy, creating incentives forimproving energy efficiency and minimizing environmental footprints.

Examples of regulation impacting energy consumers and producers includeCalifornia's Low Carbon Fuel Standard (LCFS) and the U.S. EPA's CleanPower Plan. The LCFS models life cycle fuel pathways to assign a CarbonIntensity (CI) to fuels that reflects a fuel's carbon dioxide emissions.A fuel producer's pathway, reflecting the CI for their process,generates credits or requires the purchase of credits from otherproducers to meet California's CI targets. These credits are traded onan exchange that establishes their value and permits monetization byproducers. Improvements in process energy efficiency are directlyrewarded through the LCFS system, incentivizing energy efficiencyinvestments. This system, and similar systems under consideration bygovernmental authorities, directly reward producers for reducing theirenergy requirements, even when low energy prices provide little or noincentive to make such investments.

Bio-fermentation products, which include biofuels, are the result of theinvestment of energy by growing a biological raw material which is thenconverted by chemical processing to a purified liquid fuel, with eachstep requiring energy-intensive stages which include distillation.Conventional, first-generation methods employed at a bio-distilleryplant expend significant energy in distillation. The inefficiency ofthese methods negatively impacts producer economics as well as theenvironmental footprint ascribed to the process.

Improvements in overall energy efficiency and optimization are stillneeded commercially for new or existing distilleries, or new or existingbiorefineries employing distillation.

SUMMARY OF THE INVENTION

Some variations of the present invention provide a method of modifying adistillery or biorefinery, wherein the distillery or biorefineryconverts biomass into a biofuel or biochemical, and wherein the biofuelor biochemical is purified by distillation, the method comprising:

(i) introducing a mechanical vapor recompression (MVR) unit to recoverheat of the distillation and provide a reduction in process thermalenergy usage in the distillery or biorefinery; and

(ii) introducing a combined heat and power (CHP) system having a CHPengine, to provide mechanical and electrical energy for driving the MVRunit, wherein residual waste heat of the CHP engine offsets the processthermal energy usage in the distillery or biorefinery, in conjunctionwith the MVR unit; and wherein integration of the MVR unit with the CHPsystem is balanced to optimize process energy requirements, processcarbon intensity, and/or process energy costs.

In some embodiments, the MVR unit comprises multiple compressors,wherein cascaded heat from the distillation is integrated with multiplestillage evaporations and optionally dehydration, and wherein compressedbiofuel or biochemical vapors and generated steam are returned to thedistillation.

In some embodiments, the MVR unit comprises multiple compressors,wherein cascaded heat from the distillation is integrated with multiplestillage evaporations including a first evaporator, wherein compressedsteam from the first evaporator is optionally split between thedistillation and a part of the multiple stillage evaporations, andwherein the distillation and at least a portion of the multiple stillageevaporations are operated at equal or near-equal pressure, therebyallowing a compressor stage to cascade heat of evaporation between thedistillation and the multiple stillage evaporations and optionallyvapor-phase dehydration.

In some embodiments, MVR unit comprises multiple compressors, whereincascaded heat from multiple stillage evaporations to the distillation isintegrated with compression of steam from at least onereboiler-evaporator to drive the distillation and partial evaporation,wherein the distillation and the partial evaporation are operated suchthat evaporation pressure is higher than distillation pressure, therebyallowing compressor stages to cascade the heat of evaporation into thedistillation. The dehydration is preferably integrated with thecompression of the portion of distillation vapors passed at sufficientpressure to become the final product from the dehydration.

The MVR unit may be sized or operated with a standard steam generatorfor reduction of thermal energy required in the distillation,evaporation, and dehydration wherein the standard steam generator isoperated at a reduced rate as a result of reduction in steam energydemand due to energy recovered by the MVR unit.

The CHP engine may be sized or operated in concert with (i) mechanicaldemand of the MVR unit and (ii) thermal energy demand of the distilleryor biorefinery, wherein at least some of the thermal energy demand ofthe distillery or biorefinery is provided by waste heat recovered by theCHP system.

The integration of the MVR unit with the CHP system allows balancing ofuse in the distillery or biorefinery of process fuel energy andelectrical energy unit price. For example, process energy costs may beminimized based on relative market pricing of the process fuel energyand the electrical energy. Optionally, total process energy is notminimized.

The integration of the MVR unit with the CHP system allows minimizationof carbon intensity of the distillery or biorefinery through selectiveusage of electricity and thermal fuel to minimize total carbon intensityof process energy. In some embodiments, process energy costs are notminimized based on relative market pricing of the process fuel energyand the electrical energy and the individual carbon intensitiesallocated to thermal and electrical process energy lifecycles.

The present invention also provides a process comprising, or adaptedfor, any of the disclosed methods. The biofuel or biochemical may beselected from the group consisting of methanol, ethanol, 1-propanol,2-propanol, n-butanol, isobutanol, 2-butanol, tert-butanol, acetone, andcombinations thereof.

In addition, the present invention provides systems configured to carryout the disclosed methods. Some variations provide a distillery orbiorefinery comprising such a system. The system may be a retrofit to anexisting plant. In other embodiments, the biorefinery is a greenfieldplant.

Some variations provide an energy-efficient system configured for adistillery or biorefinery, wherein the distillery or biorefinery iscapable of converting biomass into a biofuel or biochemical, and whereinthe distillery or biorefinery includes distillation configured to purifythe biofuel or biochemical, the system comprising:

(i) a mechanical vapor recompression (MVR) sub-system configured torecover heat of the distillation and provide a reduction in processthermal energy usage in the distillery or biorefinery; and

(ii) a combined heat and power (CHP) sub-system having a CHP engine,configured to provide mechanical and electrical energy for driving theMVR sub-system, wherein the CHP sub-system and the MVR sub-system areintegrated and configured so that residual waste heat of the CHP engineoffsets the process thermal energy usage in the distillery orbiorefinery.

In some embodiments, the MVR unit comprises multiple compressors,wherein cascaded heat from the distillation is integrated with multiplestillage evaporations and dehydration, and wherein compressed biofuel orbiochemical vapors and generated steam are returned to the distillationwithin the system.

In certain embodiments, the MVR unit comprises multiple compressors,wherein cascaded heat from the distillation is integrated with multiplestillage evaporations including a first evaporator, wherein compressedsteam from the first evaporator is optionally split between thedistillation and a part of the multiple stillage evaporations, andwherein a compressor stage is configured to cascade heat of evaporationbetween the distillation and the multiple stillage evaporations.

In some embodiments, the MVR unit comprises multiple compressors,wherein cascaded heat from multiple stillage evaporations to thedistillation is integrated with compression of steam from at least onereboiler-evaporator to drive the distillation and partial evaporation,and wherein compressor stages are configured to cascade the heat ofevaporation into the distillation.

In some embodiments, the MVR unit comprises multiple compressors,wherein the cascaded heat from the distillation is integrated to drivethe vapor-phase dehydration.

The MVR unit may be configured with a standard steam generator to reducethermal energy required in the distillation. The CHP engine may be sizedin concert with (i) mechanical demand of the MVR unit and (ii) thermalenergy demand of the distillery or biorefinery, wherein waste heatrecovered by the CHP system provides at least some of the thermal energydemand of the distillery or biorefinery.

Other variations of the invention provide a biofuel or biochemicalproduct produced by a process comprising a method of modifying adistillery or biorefinery, wherein the distillery or biorefineryconverts biomass into the biofuel or biochemical, and wherein thebiofuel or biochemical is purified by distillation, the methodcomprising:

(i) introducing a mechanical vapor recompression (MVR) unit to recoverheat of the distillation and provide a reduction in process thermalenergy usage in the distillery or biorefinery; and

(ii) introducing a combined heat and power (CHP) system having a CHPengine, to provide mechanical and electrical energy for driving the MVRunit, wherein residual waste heat of the CHP engine offsets the processthermal energy usage in the distillery or biorefinery, in conjunctionwith the MVR unit; and wherein integration of the MVR unit with the CHPsystem is balanced to optimize process energy requirements, processcarbon intensity, and/or process energy costs.

BRIEF DESCRIPTION OF THE FIGURES

Each of FIG. 1, FIG. 2, FIG. 3, FIG. 4, FIG. 5, FIG. 6, FIG. 7, FIG. 8and FIG. 9 is a schematic drawing, showing process flows for adistillery or biorefinery, with two hashed boxed areas. The left hashedline area is labeled as “Standard Distillery Section I” and the righthashed line area is labeled as “Compound MVR-CHP Section II.” Section Iencompasses a distillery flow diagram, and Section II encompasses theadded mechanical vapor (re)compression (“MVR”) and with combined heatand power (“CHP”) of variations of the invention. The schema splitsSection I and Section II at the distillation tower, with standardsteam-driven distillation on the left side of the tower in Section I andon the right side of the tower mechanical vapor compression withcombined heat and power (MVR-CHP) in Section II.

FIG. 1 is a schematic drawing in which Section II depicts a processwherein the waste heat from the CHP is used to generate process steamthrough Heat Recovery for Steam Generation (HRSG), with the generatedsteam being used to meet steam demands of the distillery.

FIG. 2 is a schematic drawing in which Section II depicts a process inwhich the waste heat from the CHP is used to make additional processsteam through Heat Recovery for Steam Generation (HRSG), with theadditional process steam being used to meet the steam demand of thedistillery and with a portion of the CHP waste heat being used todirectly dry the distillery co-products.

FIG. 3 is a schematic drawing in which Section II depicts a process inwhich the waste heat from the CHP is exclusively used to directly drythe distillery co-products.

FIG. 4 is a schematic drawing in which Section II depicts a process inwhich the waste heat from the CHP is used to generate additional processsteam by Heat Recovery for Steam Generation (HRSG), with the additionalsteam used to generate additional electrical power in a steam turbine tomeet further electrical demand of the distillery or to sell onto thepower grid. The low-pressure steam exiting the co-generation turbine isused as process steam to meet the process steam demand of thedistillery.

FIG. 5 is a schematic drawing in which Section II depicts a process inwhich the distillation vapors are passed to a multi-effect evaporationprocess with the steam from the final effect compressed and passed tothe distillation. This integration of MVR with evaporation together withthe CHP is implied for the process configurations described in FIGS. 1,2, 3, and 4.

FIG. 6 is a schematic drawing in which Section II depicts a process bywhich distillation vapors are passed to a multi-effect evaporationprocess with the biofuel or biochemical vapors condensing in the firsteffect. The produced steam passes to multiple compressor stages, withthe first compressor stage intake passing from the lowest-pressureeffect evaporator, passing steam on to another effect where it iscompressed and passes to the later evaporators and the distillationprocess. In the distillation process, the pressure of the distillationand the high-pressure evaporation effect are preferably operated at acommon pressure, allowing one common compressor. This integration of MVRwith evaporation is implied for the process configurations described inFIGS. 1, 2, 3, and 4.

FIG. 7 is a schematic drawing in which Section II depicts a process bywhich the evaporation-generated steam vapors are passed into thedistillation to drive the distillation process, with the resultingalcohol vapors begin condensing in the condenser of Section I or passingto the MVR of Section II. The evaporator steam passes to compressorstages, with the steam in the compressor stage intake coming from theeffect of the evaporator, and the higher-pressure output steam of thecompressor passing part of the steam back to the evaporator effect andpart to the distillation. The biofuel/biochemical vapors of thedistillation process are the intake to a compressor with thehigher-pressure biofuel/biochemical vapors passing to a reboiler and thegenerated steam passing to the distillation. In the distillationprocess, the pressure of the distillation and the high-pressureevaporation effect are operated preferably with the distillation atlower pressure than the evaporation, allowing the distillation alcoholcompressed vapor pressure output and the evaporator steam compressedvapor output to have a common pressure to drive the distillation. Thisintegration of distillation MVR with evaporation MVR is implied for theprocess configurations together with CHP as described in FIGS. 1, 2, 3,and 4.

FIG. 8 is a schematic drawing in which Section II depicts a process bywhich the azeotrope vapors from a two-phase distillation system arebeing condensed in the condenser of Section I or passing to the MVR ofSection II. The biofuel/biochemical vapors (which in some embodimentsare azeotrope biofuel/biochemical vapors) from the two-phasedistillation pass into the compressor stages intake, and thehigher-pressure output vapors of the compressors pass in part to thecondensing side of a reboiler which generates steam for the aqueoustower and the other part of the two-phase distillation. The remainingbiofuel/biochemical vapors of the distillation process pass to theintake to a compressor, resulting in an output of higher-pressurebiofuel/biochemical vapors passing to a second reboiler, wherein thegenerated organic vapors pass to the organic distillation tower. Thisintegration of two-phase distillation with MVR driving a reboiler forthe aqueous distillation and MVR also driving a reboiler is implied forthe process configurations together with CHP as described in FIGS. 1, 2,3, and 4.

FIG. 9 is a schematic drawing in which Section II depicts a process bywhich distillation vapors are passed to a MVR system, where a portion ofthe compressed distillation top product vapors pass to a multi-effectevaporation process with the azeotrope biofuel or biochemical vaporscondensing. The generated steam is returned to the distillation and theremaining vapors further compressed to the dehydration system, whereinthe condensation of the biofuel/biochemical vapors and/or generatedsteam is returned to drive the biorefinery or distillery. Thisintegration of distillation MVR with dehydration MVR is implied for theprocess configurations described in FIGS. 1, 2, 3, 4, 5, 6 and 7.

These and other embodiments, features, and advantages of the presentinvention will become more apparent to those skilled in the art whentaken with reference to the following detailed description.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Certain embodiments of the present invention will now be furtherdescribed in more detail, in a manner that enables the claimed inventionso that a person of ordinary skill in this art can make and use thepresent invention. All references herein to the “invention” shall beconstrued to refer to non-limiting embodiments disclosed in this patentapplication.

Unless otherwise indicated, all numbers expressing conditions,concentrations, yields, and so forth used in the specification andclaims are to be understood as being modified in all instances by theterm “about.” Accordingly, unless indicated to the contrary, thenumerical parameters set forth in the following specification andattached claims are approximations that may vary depending at least uponthe specific analytical technique. Any numerical value inherentlycontains certain errors necessarily resulting from the standarddeviation found in its respective testing measurements.

As used in this specification and the appended claims, the singularforms “a,” “an,” and “the” include plural referents unless the contextclearly indicates otherwise. Unless defined otherwise, all technical andscientific terms used herein have the same meaning as is commonlyunderstood by one of ordinary skill in the art to which this inventionbelongs. If a definition set forth in this section is contrary to orotherwise inconsistent with a definition set forth in patents, publishedpatent applications, and other publications that are incorporated byreference, the definition set forth in this specification prevails overthe definition that is incorporated herein by reference.

The term “comprising,” which is synonymous with “including,”“containing,” or “characterized by” is inclusive or open-ended and doesnot exclude additional, unrecited elements or method steps. “Comprising”is a term of art used in claim language which means that the named claimelements are essential, but other claim elements may be added and stillform a construct within the scope of the claim.

As used herein, the phrase “consisting of” excludes any element, step,or ingredient not specified in the claim. When the phrase “consists of”(or variations thereof) appears in a clause of the body of a claim,rather than immediately following the preamble, it limits only theelement set forth in that clause; other elements are not excluded fromthe claim as a whole. As used herein, the phrase “consisting essentiallyof” limits the scope of a claim to the specified elements or methodsteps, plus those that do not materially affect the basis and novelcharacteristic(s) of the claimed subject matter.

With respect to the terms “comprising,” “consisting of,” and “consistingessentially of,” where one of these three terms is used herein, thepresently disclosed and claimed subject matter may include the use ofeither of the other two terms. Thus in some embodiments not otherwiseexplicitly recited, any instance of “comprising” may be replaced by“consisting of” or, alternatively, by “consisting essentially of.”

The concept of mechanical vapor compression (equivalently herein,“mechanical vapor recompression” or MVR) in distillation has beendeployed in reducing process requirements in refining for many decades.It has also been widely deployed in water desalination and processevaporation. This method of energy recovery has been rarely utilized,however, in the distillation processes of bio-fermentation producers. Inaddition, combined heat and power (CHP) has not been widely used inbiofuels distilleries as advances in process design have significantlyreduced producers' electrical demand to about one-fifth of the totalprocessing energy, reducing incentives.

Some variations of the invention are premised on the realization thatthe energy consumed in bio-fermentation distillation can be reduced byprocess and system configurations that recycle distillation heat throughthe application of mechanical vapor compression and combined heat andpower methods as disclosed herein. The combination of mechanical vaporcompression and combined heat and power is preferably configured as afully redundant retrofit that leverages existing process equipmentinvestment. Compression reduces the total thermal process energyrequirement of the plant via recovering the otherwise rejected heats ofvaporization, and the mechanical energy required in the compressionmethod is provided from combined heat and power methods. Electricalenergy and waste heat of the combined heat and power system is used tooffset the plant's electrical demand and process thermal energyrequirements.

The invention relates to the combination of distillation, compression,and combined heat and power methods, wherein the total reduction of thepurchased electrical and thermal process energy can be optimized throughbalancing energy usage and conversions, in a manner that minimizes theproduction energy usage, cost, and environmental impact per gallon ofproduct generated. The ratio of process electrical energy purchased fromthe power grid and the process thermal energy fuel purchased from asupplier may be managed through accounting for the costs of each form ofenergy relative to the production cost and reduction in usage availablefrom the invention. The invention provides the option of varying theamount of electrical power generated through the combined heat and powerprocess to optimize process efficiency using electrical grid purchasesto provide shortfalls or cyclic demands that either exceed the plant'scapacity or impose inefficiencies that justify such purchases. The wasteheat of the combined heat and power may be passed as recaptured heat toprocesses within and outside of the distillation stage.

The meaningful and sizable reduction in process thermal energy usage ofthese plants through addition of the invention will also substantiallyreduce the carbon intensity ascribed to the plant's process. Thedistillation energy in a standard bio-fermentation distillery withoutmechanical vapor compression represents from 40% to 60% of the totalprocess energy. Mechanical vapor compression, when used in distillation,recycles the heat of distillation by a closed heat pump, as disclosedfor example in U.S. Pat. Nos. 4,340,446, 4,422,903, 4,539,076,4,645,569, 4,692,218, 4,746,610, 5,294,304, 7,257,945, 8,101,217,8,101,808, 8,114,255, 8,128,787, 8,283,505, 8,304,588, 8,535,413, and8,614,077, which are hereby incorporated by reference herein.

Distillation is generally the largest consumer of energy in a plantutilizing bio-fermentation due to the necessarily dilute beer producedby micro-organisms. The large amount of water in the beer must beseparated from the desired product through distillation. Generally, thedistillation system is heated by steam produced from combusting a fuelin a boiler. Vapors collected from the distillation system are cooled ina condenser where they release their latent heat of condensation. Thisenergy is lost to the condenser's cooling water that, in turn, releasesits heat to the atmosphere. By rerouting the vapors prior to theirintroduction into the condenser and increasing the pressure andtemperature of the vapors through compression, forcing the superheatedvapors to condense in a reboiler, the latent heat of condensation can becaptured and transferred to water used to generate steam. This generatedsteam from the reboiler can be directly recycled to the distillationtower, as described in FIGS. 1, 2, 3, and 4.

In some embodiments, the generated steam from the reboiler may be usedto drive an evaporation system wherein pressure drops within theevaporation effects may require additional compression as described inFIG. 5. In some embodiments, the evaporation and distillation may bedriven from a common compression system, passing steam to an evaporatoroperated at a common pressure with the distillation as described in FIG.6. In some embodiments, the distillation compressor vapors pass to thereboiler as part of the evaporation, passing steam back to thedistillation and the evaporation passing steam to the distillation as inFIG. 7. In some embodiments the distillation vapors are partiallycondensed in the reboiler with the remaining vapors compressed forvapor-phase dehydration with the anhydrous vapor product of dehydrationcondensing in a reboiler with the generated steam passed back to thedistillery or bio-refinery. In some embodiments, two-phase distillationcompressor azeotrope vapors are balanced between two reboilers with aportion of the vapors condensing in one reboiler for water, whichgenerates steam for driving the aqueous distillation tower, and theremaining compressed vapors passing to another reboiler for the organicalcohol to condense by producing organic vapors for driving the organicdistillation tower as in FIG. 8.

In the past, the high cost of driving the vapor compressor limited theeconomic advantages that could be gained. More efficient motors withintegrated heat recapture used for generating electricity to driveelectric compressor drive motors or directly driving the compressor havebecome available, vastly improving process cost and efficiency. Usingsteam from an existing steam generation system to supplant steamgenerated through vapor compression can allow the motors increase theirtime operating at peak efficiency. Electricity provided by excessgeneration not needed for vapor compression can replace electricityformerly supplied by a utility and motor heat recapture can provideadditional process heat. Optimizing the efficiency of the motors andusing system steam and utility electricity to trim output can achieve anoptimized system configuration that minimizes total energy usage, cost,and carbon dioxide emissions. System reliability is improved throughretention of the existing steam generation and distillation system thatcan be operated during maintenance of the retrofit vapor compressionsystem.

In a system utilizing mechanical vapor compression, the mechanicalenergy of the compression is typically equivalent to about 15% to 20% ofthe thermal energy required for the identical distillation processwithout compression. The energy advantage in mechanical vaporcompression will be typically about 5:1, or in various embodiments,about 3:1, 4:1, 5:1, 6:1, 7:1 or higher. The market values of thermalenergy and electricity varies by market with electrical power costs andnatural gas thermal energy costs showing a historic cost relationshipper unit of energy of 3:1 to 8:1. The relative unit energy pricerelationship between thermal energy and electrical power determines theeconomic value of mechanical compression in distillation. The equipmentinvestment costs of compression equipment are an additional determinantof the economic advantage of mechanical vapor compression distillation.High electrical costs for driving the compression system may outweighthe savings provided by reduced thermal energy demand.

The typically high ratio of electrical power costs per unit energy tothermal natural gas costs per unit energy supports the use of highefficiency combined heat and power in bio-fermentation distilleryprocessing. Electricity can be generated at a lower cost than thatoffered by local utility providers, and waste heat from the engine iseasily directed into the many processes within the plant that requirethermal energy not included in the distillation stage.

In preferred embodiments, the invention integrates the advantageprovided by reducing the cost of mechanical energy through use of thecombined heat and power system with the reduced thermal energy requiredin the distillation system achieved by mechanical vapor compression. Thedesign's optimization is balanced between current energy pricing andexpected future trends in energy pricing and environmental regulation.The invention's focus on integration of mechanical vapor compression indistillation and combined heat and power provides multiple options forthe design and sizing of the major components and uses of the waste heatfrom the combined heat and power. Several examples are provided todemonstrate possible configurations of the integrated system utilizingmechanical vapor compression in distillation and combined heat andpower.

Some variations of the present invention provide a method of modifying adistillery or biorefinery, wherein the distillery or biorefineryconverts biomass into a biofuel or biochemical, and wherein the biofuelor biochemical is purified by distillation, the method comprising:

(i) introducing a mechanical vapor recompression (MVR) unit to recoverheat of the distillation and provide a reduction in process thermalenergy usage in the distillery or biorefinery; and

(ii) introducing a combined heat and power (CHP) system having a CHPengine, to provide mechanical and electrical energy for driving the MVRunit, wherein residual waste heat of the CHP engine offsets the processthermal energy usage in the distillery or biorefinery, in conjunctionwith the MVR unit; and

wherein integration of the MVR unit with the CHP system is balanced tooptimize process energy requirements, process carbon intensity, and/orprocess energy costs.

In some embodiments, the MVR unit comprises multiple compressors,wherein cascaded heat from the distillation is integrated with multiplestillage evaporations, and wherein compressed biofuel or biochemicalvapors and generated steam are returned to the distillation.

In some embodiments, the MVR unit comprises multiple compressors,wherein cascaded heat from the distillation is integrated with multiplestillage evaporations including a first evaporator, wherein compressedsteam from the first evaporator is optionally split between thedistillation and a part of the multiple stillage evaporations, andwherein the distillation and at least a portion of the multiple stillageevaporations are operated at equal or near-equal pressure, therebyallowing a compressor stage to cascade heat of evaporation between thedistillation and the multiple stillage evaporations.

In some embodiments, the MVR unit comprises multiple compressors,wherein cascaded heat from multiple stillage evaporations to thedistillation is integrated with compression of steam from at least onereboiler-evaporator (e.g., from two or more reboiler-evaporators whoseoutput is combined) to drive the distillation and partial evaporation,wherein the distillation and the partial evaporation are operated suchthat evaporation pressure is higher than distillation pressure, therebyallowing compressor stages to cascade the heat of evaporation into thedistillation.

In some embodiments, the MVR unit comprises multiple compressors,wherein cascaded heat from the distillation is partially recompressed toa reboiler where the condensed distillation top product is recovered forreflux and the remaining vapors are passed to the dehydration, with thepressure of the vapors being sufficient (optionally, additionalcompressors are used) to raise the pressure as needed to drive thedehydration.

The MVR unit may be sized or operated with a standard steam generator toreduce thermal energy required in the distillation, and wherein thestandard steam generator is operated at a reduced rate as a result ofreduction in steam energy demand due to energy recovered by the MVRunit.

The CHP engine may be sized or operated in concert with (i) mechanicaldemand of the MVR unit and (ii) thermal energy demand of the distilleryor biorefinery, wherein at least some of the thermal energy demand ofthe distillery or biorefinery is provided by waste heat recovered by theCHP system.

The integration of the MVR unit with the CHP system allows balancing ofuse in the distillery or biorefinery of process fuel energy andelectrical energy unit price. For example, process energy costs may beminimized based on relative market pricing of the process fuel energyand the electrical energy. Optionally, total process energy is notminimized.

The integration of the MVR unit with the CHP system allows minimizationof carbon intensity of the distillery or biorefinery through selectiveusage of electricity and thermal fuel to minimize total carbon intensityof process energy. In some embodiments, process energy costs are notminimized based on relative market pricing of the process fuel energyand the electrical energy and the individual carbon intensitiesallocated to thermal and electrical process energy lifecycles.

The present invention also provides a process comprising, or adaptedfor, any of the disclosed methods. The biofuel or biochemical may beselected from the group consisting of methanol, ethanol, 1-propanol,2-propanol, n-butanol, isobutanol, 2-butanol, tert-butanol, acetone, andcombinations thereof. The biofuel or biochemical may also be selectedfrom organic acids, such as lactic acid, higher alcohols (e.g., C₅₊alcohols), alkanes, etc. As used herein, “biofuel,” “biochemical,”biofuel/biochemical” and the like shall refer to one or morefermentation products of interest. Co-products include, but are notlimited to, DDG, DDGS, sugars, lignin, still bottoms, and energy.

In addition, the present invention provides systems configured to carryout the disclosed methods. Some variations provide a distillery orbiorefinery comprising such a system. The system may be a retrofit to anexisting plant. In other embodiments, the biorefinery is a greenfieldplant.

In various embodiments, the biomass feedstock may be selected fromagricultural crops and/or agricultural residues. In some embodiments,agricultural crops are selected from starch-containing feedstocks, suchas corn, wheat, cassava, rice, potato, millet, sorghum, or combinationsthereof. In some embodiments, agricultural crops are selected fromsucrose-containing feedstocks, such as sugarcane, sugar beets, orcombinations thereof.

Lignocellulose biomass may also be used as the biomass feedstock.Lignocellulose biomass includes, for example, plant and plant-derivedmaterial, vegetation, agricultural waste, forestry waste, wood waste,paper waste, animal-derived waste, poultry-derived waste, and municipalsolid waste. In various embodiments of the invention, the biomassfeedstock may include one or more materials selected from: timberharvesting residues, softwood chips, hardwood chips, tree branches, treestumps, knots, leaves, bark, sawdust, off-spec paper pulp, cellulose,corn, corn stover, wheat straw, rice straw, sugarcane bagasse,switchgrass, miscanthus, animal manure, municipal garbage, municipalsewage, commercial waste, grape pumice, almond shells, pecan shells,coconut shells, coffee grounds, grass pellets, hay pellets, woodpellets, cardboard, paper, carbohydrates, plastic, and cloth. Mixturesof starch-containing and/or sucrose-containing feedstocks withcellulosic feedstocks, for example, may be used.

Some variations provide an energy-efficient system configured for adistillery or biorefinery, wherein the distillery or biorefinery iscapable of converting biomass into a biofuel or biochemical, and whereinthe distillery or biorefinery includes distillation configured to purifythe biofuel or biochemical, the system comprising:

(i) a mechanical vapor recompression (MVR) sub-system configured torecover heat of the distillation and provide a reduction in processthermal energy usage in the distillery or biorefinery; and

(ii) a combined heat and power (CHP) sub-system having a CHP engine,configured to provide mechanical and electrical energy for driving theMVR sub-system, wherein the CHP sub-system and the MVR sub-system areintegrated and configured so that residual waste heat of the CHP engineoffsets the process thermal energy usage in the distillery orbiorefinery.

In some embodiments, the MVR unit comprises multiple compressors,wherein cascaded heat from the distillation is integrated with multiplestillage evaporations, and wherein compressed biofuel or biochemicalvapors and generated steam are returned to the distillation within thesystem.

In certain embodiments, the MVR unit comprises multiple compressors,wherein cascaded heat from the distillation is integrated with multiplestillage evaporations including a first evaporator, wherein compressedsteam from the first evaporator is optionally split between thedistillation and a part of the multiple stillage evaporations, andwherein a compressor stage is configured to cascade heat of evaporationbetween the distillation and the multiple stillage evaporations.

In some embodiments, the MVR unit comprises multiple compressors,wherein cascaded heat from multiple stillage evaporations to thedistillation is integrated with compression of steam from at least onereboiler-evaporator to drive the distillation and partial evaporation,and wherein compressor stages are configured to cascade the heat ofevaporation into the distillation.

The MVR unit may be configured with a standard steam generator to reducethermal energy required in the distillation. The CHP engine may be sizedin concert with (i) mechanical demand of the MVR unit and (ii) thermalenergy demand of the distillery or biorefinery, wherein waste heatrecovered by the CHP system provides at least some of the thermal energydemand of the distillery or biorefinery.

The terms “distillery,” “distillery process,” and “distillery plant”herein refer to a bio-fermentation plant or process in which raw biomassis processed through stages leading to a fermentation stage and on toseparation of the fermentation products using distillation separation asat least one stage for product purification. The term “biorefinery”herein refers to a plant or process in which raw biomass is processedthrough stages leading to a fermentation stage and on to separation ofthe fermentation products using distillation separation as at least onestage for product purification, wherein the fermentation product may beany biofuel or biochemical, and wherein the biomass feedstock may belignocellulosic biomass. All instances of “distillery” in thisspecification may be replaced with “biorefinery,” and vice-versa, insome embodiments.

The term “total process energy” herein refers to the thermal energyrequired to raise process steam by burning fuels, or direct heating ofprocesses by burning fuels, plus the electrical energy required formechanical power used in pumping, stirring, grinding, etc.

The terms “addition of mechanical vapor compression in distillation” and“addition of combined heat and power” herein refer to a retrofit oraugmentation of a standard distillery or biorefinery that uses astandard thermally driven distillation process, to a distillery orbiorefinery enhanced with the option of diverting vapors into amechanical vapor compression system integrated into the distillery orbiorefinery, including a combined heat and power system.

The terms “mechanical vapor compression in distillation” and “integratedcombined heat and power” herein refer to the addition of mechanicalvapor compression and combined heat and power, to provide the ability tooperate with various combinations of mechanical vapor compression,standard process steam generated by the original system, and combinedheat and power to receive the maximum advantage from each of the twoadded processes (i.e., mechanical vapor compression in distillation andcombined heat and power).

The terms “bio-fermentation distillery process stages,” as found in eachof the schematic flow diagrams (FIGS. 1, 2, 3, 4, 5, 6, 7, 8 and 9)herein, refer generally to stages 1 through 9 as follows:

Stage 1: A milling stage or device(s) which process biomass byphysically dividing the feedstock materials with a grinding or extrusionprocess which exposes the internal parts of the feedstock;

Stage 2: A cooking stage which uses various combinations of controlledtemperatures, pressures, stirring, and special chemical conditioningwith acidic or basic chemicals, and/or enzymes (e.g., amylase orcellulase enzymes), for breaking polysaccharides into glucosides;

Stage 3: A heat exchanger stage which cools the cook solution tofermentation temperatures and conversely heats post-fermentationproducts up to distillation temperatures;

Stage 4: A fermentation stage wherein the cook solution has biologicalagents introduced to ferment the sugars to the desired biochemicalproduct(s);

Stage 5: A distillation stage, after the fermented products have beenpre-heated in the heat exchanger of stage 3, where the biochemical topproducts are separated from the fermentation waters;

Stage 6: A condensation stage where the vapors from the distillationstage 5 are passed on to a cooling system where the heat of distillationis discarded, or where the vapors are mechanically compressed to recoverthe heat of distillation and cascade the heat to, or from, stages 7 andstage 8;

Stage 7: A stillage handling stage for the bottom product of thedistillation or aqueous distillation stage 5, for recovering wetco-products of the fermentation to be further processed with possibledrying and, potentially, evaporation to concentrate thin stillage;

Stage 8: An optional dehydration stage for the biochemical products fromthe distillation stage 5, if the distillation stage 5 does notsufficiently separate the biochemicals from the fermentation water toreach the desired purity; and

Stage 9: An optional storage stage where the high-grade biochemical goesto storage, if the biochemical product is not immediately shipped fromthe plant (e.g., if not directly pumped into tank trucks or rail cars).

Herein the “general distillery process” refers in total to mean the manystages which all require energy in the form of thermal/steam ormechanical/electrical, wherein the thermal and mechanical energy is inpart or in full supplied by a combined heat and power plant. The portionof the energy that is not provided from the combined heat and powerplant is derived from the electrical power grid as purchased power orfuel from a supplier as will be found in a plant without mechanicalvapor compression in distillation and/or without combined heat andpower, or in the case where the vapor compression in distillation and/orcombined heat and power are not being used.

The process energy distribution in the distillery depends on theaforementioned stages 1 through stage 9, with the exception of thedistillation as stage 5, wherein the use of the mechanical vaporcompression reduces the thermal-steam energy for the distillation,evaporation, and optionally dehydration. Distillation normallyrepresents the largest energy-consuming stage in the distillery andtherefore provides the largest potential opportunity for reducing thetotal energy of the process. With the exception of the mechanical andthermal energy demand of the distillation in stage 5, the other stagesrequire lesser amounts of mechanical energy and/or thermal energy whichmay be met by the combined heat and power system.

Examples of the different options available to supply thethermal-mechanical energy produced from the combined heat and powersystem to the distillery are shown in the nine schematic drawings inFIGS. 1, 2, 3, 4, 5, 6, 7, 8 and 9. The thermal andmechanical-electrical distribution of the heat and power is proposed invaried uses for the distillery stages. In these drawings, like numeralsrefer to like apparatus, streams, or unit operations.

The invention in some embodiments is shown in FIGS. 1, 2, 3, 4, 5, 6, 7,8 and 9, having a common process path with the process effluent flowbeginning with the raw biomass being stored in a bin 1, which deliversthe biomass substrate via delivery duct 2 to a milling/extrusion process3, which renders the substrate to a biomass flour having a suitable sizeso that the internal portions of the raw biomass are exposed forchemical conversion and processing. The biomass flour passes by a duct 4with additional chemicals, which may include for example acids orenzymatic agents, and ultimately to the cooking process in vessel 6.

The biomass flour passing from the duct 4 is mixed with process water bya process line 5, where the mixed flour and process water enters thecooking vessel 6. Within the cooking vessel 6, the application oftemperature/pressure is delivered by a process steam line 7, andchemicals in a cooking vessel 6, proceeding with the chemical conversionto fermentable saccharides with the assistance of a stirring system 8.

The product of chemically converted slurry from the cooking vessel 6,passes via process line 9, to a heat exchanger 10, where the heatinvested into the cook process is removed prior to the fermentation,since the fermentation typically occurs at lower temperatures thancooking. The cook slurry, after being cooled in the heat exchanger 10,is transported by a process line 11 which is controlled via a valvesystem 12, where the cook slurry passes to a battery of fermenters 13,which may be configured as a batch or continuous fermentation system,with a stirring system 14.

The finished fermentation product, that contains the desired biochemicalproduct as a watery solution with other side products, passes via avalve controlled line 15, to process line 16, where the biochemicalproduct of the fermentation is heated via heat exchanger 10, that passesheat from the high-temperature cook slurry going into the fermentationsystem to the fermentation product leaving the fermentation systempassing via a process line 17, to the distillation system 18 (FIGS. 1through 7) or 18 a (aqueous distillation system, FIG. 8). In FIG. 8, thedistillation system 18(a,b) includes an aqueous distillation system 18 aand an organic distillation system 18 b.

The distillation system 18 or 18(a,b) further processes the wateryfermented solution to further separate desired biochemical products fromthe water. The distillation system 18 or 18(a,b) yields a top productwhich has a biochemical product composition that in some embodimentsapproaches an azeotrope with water, or which may be near purity withrespect to the desired biochemical. The azeotrope or nearly purebiochemical product passes out of the distillation system as vapors viaa vapor line(s) 19 or 19(a,b). The distillation vapor line(s) 19 or19(a,b) leads to two different process paths. The existing process pathis labeled “Standard Distillery Section I.” The retrofit or enhancementsystem is labeled “Compound MVR-CHP Section II.”

In Section I, the vapors pass to a standard distillation condenser 20,with the condensed distillation top product passing via liquid line 21to a holding reflux tank 22 (reflux tank in FIG. 1 through FIG. 7 andFIG. 9, and phase-separation tank in FIG. 8).

The distillation condenser system 20 is cooled by a cooling system 23,(cooling tower). The cooling water from the cooling system 23 passes viaa pipe 24 to a circulation pump 25, which pumps the cooling water by avalve controlled pipe 26, to the condenser 20, after which the coolingwater is returned via a pipe 27 to the cooling system 23.

The distillation top product leaving the condenser passes via the liquidline 29(a,b) to the reflux tank/buffer and then to the distillationsystem 18(a,b) as the reflux. At least a portion of the top product, asa single-phase azeotrope (as in FIGS. 1 through 7 and 9), passes back tothe distillation 18. In some embodiments, at least a portion of aphase-separable azeotrope (as in FIG. 8) passes as the total topproduct, via two separate streams based on the phase separation, passingback to the distillation towers; the heavy aqueous phase passes to theaqueous distillation 18 a via liquid line 29 a and the light organicphase passes to the organic distillation 18 b via liquid line 29 b. Thesingle-phase examples in FIG. 1 through FIG. 7 and FIG. 9 have theremainder of the condensed distillation top product from thedistillation system 18 which is not passed as reflux is the finalproduct, pure or near-pure biochemical or an azeotrope with water thatpasses from liquid line 30 to the dehydration system via line 54.

The bottom product of the distillation system, 18 or 18(a), whichcontains the heavy components as stillage, passes via a liquid line 31,to a pump 32, where the liquid passes via a line 33, which leads to twopotential paths wherein it is split between the final bottom product viaa liquid line 33, or cycled through a reboiler(s) 43(a,b) via a liquidline(s) 48(a,b), with the difference passing away from the distillationsystem, 18 or 18(a), via a liquid line 34, wherein the stillage isoptionally further processed to recover co-products having commercialvalue. Thin stillage is returned to the reboilers 43(a) and 43(b),resulting in thin stillage passing to lines 48(d) and 48(e), and thereboiler condensate from the generated steam passing as condensate tothe cook stage via line 48(c). In FIGS. 1-4, 8, and 9, line 48 is theliquid stream exiting reboiler 43 (or 43 a in the case of FIG. 8). InFIGS. 1-4, line 49 is the vapor stream exiting reboiler 43 and returningto distillation system 18.

The distillation system, 18 or 18(a,b), may in part be driven thermallyby a steam generator 35, wherein the production steam passes via a steamline 36, with a control valve 37, potentially serving other thermaldemands in the system such as steam line 7 to the cook process. Thesteam generator 35 is fueled via fuel line 200. The bidirectional steamline 38 forms a connection between the steam generator 35 and thepotential waste heat from the combined heat and power system 52 via asteam line 53. The steam line 39 is controlled by a valve 40 to deliversteam to potentially drive the distillation system, 18(a).

In Section II, the top product of the distillation system, 18 or18(a,b), passes via a vapor line(s), 19 or 19(a,b), which is potentiallysplit with the condenser system 20, passing to an optional vapor line41(a) for single-phase distillation or 41 a and 41 b for two-phasedistillation system, then passing to a compressor 42(a) for single-phasedistillation or 42 a and 42 b for two-phase distillation. Thecompressor(s) 42(a,b) receives mechanical energy from an engine driver50, receiving fuel via line 201 that produces mechanical-electricalenergy to meet the demand of the compressor(s) and/or the electricaldemand in the plant's processes. In FIGS. 1-4, compressed vapor line 42exits the compressor 42 a.

In FIG. 5, the compressor 42(a) compresses the biofuel/biochemical-richdistillate vapors that pass through vapor line 42. The compressed vaporspass to a reboiler 43(a), where they condense at a higher temperaturethan the stillage bottom products of the distillation 18, pumped by pump32 via a liquid line 48(a) to the reboiler 43(a). The stillage bottomproduct boils in the reboiler 43(a), forming steam with the steampassing via a steam line 49, to drive and meet the thermal demand of thedistillation system 18.

In FIG. 9, the compressor 42 a compresses a portion of thebiofuel/biochemical-rich distillate vapors that pass to a reboiler 43 a,where they condense at a higher temperature than the stillage bottomproducts of the distillation 18 with the remainingbiofuel/biochemical-rich distillate vapors passing to an optionalcompressor 42 b and then passing to the dehydration vapor line 61 tovapor-phase dehydration.

The reboiler(s) 43 or 43(a) condensate for single-phase distillation inFIGS. 1 through 7 and 9, and reboiler (s) 43 a and 43 c condensate forphase-separated distillation in FIG. 8, as near-pure biochemical orazeotrope, passes via liquid line 44 to a compression-side reflux tank45 in FIG. 1 through FIG. 7 and FIG. 9 or phase-separation tank 45 inFIG. 8. The condensed pure or azeotrope biochemical product passes vialiquid line 46 to the distillation system 18 as reflux, with theremainder being final top product for single-phase distillation in FIG.1 through FIG. 7 and FIG. 9 or reflux to 18 b in two-phase distillationin FIG. 8 via line 46. The condensate of the two-phase azeotropesseparate with the light liquid via line 46 to organic distillation tower18 b, and the heavy aqueous mixture to the aqueous distillation tower 18a via liquid line 30.

The single-phase distillation in FIG. 1 through FIG. 7 and FIG. 9 havingthe compressor side reflux tank 45 passes the residual condensate asfinal distillation top product via liquid line 47, to the dehydrationsystem via line 54 where FIG. 9 may pass all final biofuel orbiochemical to the dehydration as compressed vapors via 42 b to vaporline 61. In FIGS. 5-7, the bottom product from the distillation via line31 passes to pump 32 to line 33, which splits into line 33 a (thinstillage entering reboilers 43 a and 43 b) and line 34 (thin stillage asoptional product line).

The two-phase distillation system example in FIG. 8 passes the finalbiochemical bottom product from the organic distillation tower 18 b, vialiquid line 47, passing to reboiler 43 c (e.g., a reboiler/organicvaporizer) and via liquid line 54, passing to reboiler 55. The organicvapors generated in the reboiler 43 c, pass to the organic distillationtower 18 b via the vapor line 46, and from reboiler 55, the vapors arepassed to organic distillation tower 18 b the vapor line 61. Theremaining final biochemical product not passing to the reboilers, 43 cand 55, passes via the liquid line 73, to the biochemical storage tank74. Thin stillage may be recovered in line 34 and/or returned in line 33a to reboiler 43 a, as shown in FIG. 8.

The engine driving the combined heat and power system 50 generatesmechanical power for the compressor(s), 42(a,b,c), and electrical powerfor the distillery system via electrical generator 102. The waste heatfrom the engine provides a source of thermal energy to drive thedistillery, via a heat duct 51.

The waste heat from the combined heat and power system 50 passes via apiping/duct system 51, to a point where the heat is used directly or itpasses to a heat exchanger 52. The heat exchanger 52 may generate steamfrom a heat recovery steam generator (HRSG), wherein recovered heat assteam passes via steam line 51, and wherein the produced steam goes tomeet steam demands throughout the distillery via the steam line 53.Steam line 53 connects to steam line 39 going to the distillationsystem, 18(a).

Steam line 38 connects to steam line 7 that drives the cook tank 6 andconnects to steam line 56 that drives the azeotrope dehydrationvaporizer 55. Thereby, the waste heat from the combined heat and powersystem 50 provides the thermal energy required in the cook process, thedistillation process, and/or the dehydration system.

The single-phase distillation top product, for FIG. 1 through FIG. 7,passes via liquid lines 30 and 47—when an azeotrope requires furtherremoval of water to reach the desired biochemical product quality—to apressure-swing vapor-phase molecular sieve dehydration or other finaldehydration system. This system receives the azeotrope product via line54. The liquid or vapor azeotrope product moving to the dehydrationsystem from the distillation should be vaporized or superheated vaporsat an increased pressure, which occurs in the heat exchanger 55(steam-driven organic vaporizer). The steam via line 56 condenses as theazeotrope vaporizes or superheats via line 54, wherein the azeotropevapors pass via vapor line 61 to the dehydration system. The processsteam which drives the vaporizer heat exchanger 55 condenses and theliquid condensate is recycled to the steam generator 35, and/or to thewaste heat-driven steam generator (HRSG) 53 via condensate line 57passing to recycle pump 58. The recycle condensate passes to the steamgenerator 35 via condensate line 59 and/or moves via condensate line 60to the waste heat-driven HRSG 52.

The two-phase distillation, as for FIG. 8, passes the final organicproduct from the organic distillation tower 18(b) via liquid line 47.The final product passes to reboiler 43 c (e.g., a reboiler/organicvaporizer) wherein vapors are produced to drive the organic distillationtower 18 b via the vapor line 46 c, with the remainder of the organicproduct passes to the liquid line 54. The final organic liquid productmoving via line 54 passes to a reboiler 55 (steam-driven organicvaporizer) which generates vapors that pass via vapor line 46 b, whichpasses vapors to vapor line 46 c, which passes the vapors to the organicdistillation tower 18 b. The process steam which drives the vaporizerheat exchanger 55 condenses and the liquid condensate is recycled to thesteam generator 35, and/or to the waste heat-driven steam generator(HRSG) 53, via condensate line 57 passing to recycle pump 58. Therecycle condensate passes to the steam generator 35, via condensate line59 and/or moves via condensate line 60 to the waste heat-driven HRSG 52.

In the FIG. 1 through FIG. 7 and FIG. 9 single-phase distillationsystems, which produce azeotropes with excessive water, the pressurizedazeotrope distillation top product is passed to the vapor-phasedehydration system. The dehydration system is depicted as a three-bottlesystem, although the number of bottles may be two or greater. Thedescribed dehydration system passes the pressurized vapors via athree-valve system wherein one of the bottles is in dehydration modewhile the two alternative bottles are being regenerated under lowpressure. The three bottles are cycled in a round-robin style with eachbottle being used for a period based on the capacity of the dehydrationmedium, while the alternative bottles are regenerating throughapplication of a vacuum to recover the captured water. A portion of thedehydrated product is used to backflush the regenerated bottles, so theregenerated bottle can be placed back in service when the captured wateris removed.

The dehydration system, in FIG. 1 through FIG. 7 and FIG. 9, passes thepressurized vapors via vapor line 61 to a system of control valves, 62a/62 b/62 c, wherein an open valve passes the pressurized vapors to theappropriate vapor line, 63 a/63 b/63 c, which passes the product to thedehydrating bottle, 64 a/64 b/64 c, that is in service during thatperiod of operation. The dehydrated product passes through thedehydrating bottle via the exiting control valves, 65 a/65 b/65 c, tovapor line 66 as the anhydrous biochemical product.

The dehydration bottles being regenerated pass a fraction of thedehydrated vapors from the one active bottle to backflush theregenerating bottles. The low-pressure bottle is controlled by controlvalves, 67 a/67 b/67 c, with the regeneration vapors containing amixture of the regenerated water vapors and the backflush anhydrousproduct passing via the vapor line 68. The regeneration is driven by avacuum pump system 69, wherein the vapors are pumped via line 70. Thedehydration regeneration product is returned to the distillation system18 via line 71 for re-distillation of the regeneration productcontaining the backflush product.

The final anhydrous biochemical product from the dehydration passes as avapor to an anhydrous condenser reboiler 72, wherein the final productis condensed and passed via liquid line 73 to storage tank 74 (e.g.,anhydrous biochemical tank). The anhydrous condenser is cooled by thecondenser water via condensate water line 75, wherein the heated wateris vaporized to steam in the reboiler 72, with the steam passed via linesteam line 75, and wherein the steam may be used to drive the thermaldemands of the distillery.

The process steam boiler 35 has makeup water added into the condensatereturn line 60 and/or 75, via the water lines 300 and/or 301.

The electrical power grid 100 is used to meet the process electricaldemand for the milling/extrusion, cook stirring, fermentation stirring,and pumping, 101. The combined heat and power system 50, which consumesfuel via line 201, generates electrical power 102, which offsets theelectrical power grid 100. The thermal energy captured from the combinedheat and power system 50 generates additional steam via the HRSG 52,which offsets the fuel consumed in the steam generator 35 provided fuelvia line 200. The portion of recovered waste heat from the combined heatand power via line 201 reduces the fuel 200 required in the steamgenerator 35.

The combined heat and power system provides local mechanical/electricalenergy 201, and recovered waste thermal energy 52, wherein themechanical/electrical demands of the distillery can be met through theuse of local energy production via power line 102. The mechanical energyconsumed in the mechanical vapor compression compressor 42(a,b) reducesthe thermal energy demand of the distillery by reducing the steam demandin steam line 40 to the distillation 18. When Compound MVR-CHP SectionII is operated, a large portion of the steam formerly or otherwiseproduced by consuming the fuel 200, in the steam generator 35, isprovided by steam generated from heat recaptured in reboiler(s) 43(a,b)that would otherwise be lost to cooling tower 23 in Standard DistillerySection I standard operations. Operating Section II provides a netreduction in both fuel required 200 and electrical power 100. Fuelconsumed in the engine/CHP drives the compressor(s) 42(a,b), andgenerates excess electrical power 102 to meet plant needs, offsettingelectrical power 100 previously or otherwise purchased to meet plantdemand—yielding a reduction in energy demand for both fuel andelectrical power.

The example of FIG. 1 preferably sizes the combined heat and powersystem to produce mechanical and electrical energy to drive themechanical vapor compression in stage 5, referring to theabove-describes stages 1 through 9. The thermal energy of thedistillation is greatly reduced, and the electrical energy beyond theamount required to drive the compressor of the vapor compression system,is used to generate electrical power. This electrical power serves theelectrical demand of the other stages which require mechanical energysuch as pumping, stirring as in the cooking in stage 2, and fermentationin stage 4. FIG. 1 shows heat from the combined heat and power systemused to generate steam by heat recovery with steam generation, in whichthe steam is passed on to potentially all other thermally intensivestages such as the cook in stage 2, the distillation in stage 5 (for anysteam not offset by the mechanical vapor compression), and/or thedehydration in stage 8. Through this approach, the combined heat andpower may be sized to provide mechanical energy as needed in the vaporcompression with the residual power offsetting the otherwise moreexpensive grid electrical costs of the distillery stages. The resultingwaste heat meets, but does not exceed, the other thermal-steam demandsof heat-intensive stages.

The example of FIG. 2, like FIG. 1, shows the distribution of heat fromthe combined heat and power system used to produce mechanical andelectrical energy to drive the mechanical vapor compression in stage 5,wherein the thermal energy of the distillation is greatly reduced, andthe electrical energy beyond the demand to drive the compressor of thevapor compression is used to generate electrical power which goes toserve the electrical demand of the other stages which require mechanicalenergy such as pumping, stirring (as in the cooking in stage 2) andfermentation in stage 4. FIG. 2 shows a split of the heat from thecombined heat and power system used to generate steam by heat recoverywith steam generation, wherein the steam is passed on to potentially allother thermally intensive stages, such as the cook in stage 2, thedistillation in stage 5 (for any steam not offset by the mechanicalvapor compression), and/or the dehydration in stage 8. Part of the wasteheat of the combined heat and power system may be passed on to directlydry co-products of the distillery stillage in stage 7.

The example of FIG. 3 like FIG. 1 and FIG. 2 shows the distribution ofthe heat from the combined heat and power system used to producemechanical and electrical energy to drive the mechanical vaporcompression in stage 5, wherein the thermal energy of the distillationis greatly reduced, and the electrical energy beyond the amount neededto drive the compressor of the vapor compression serves the electricaldemand of the other stages which require mechanical energy such aspumping, stirring as in the cooking in stage 2, and fermentation instage 4. FIG. 3 shows the heat from the combined heat and power systemused to directly preheat process water by using the heated cooling waterfrom the power system, or by preheating the process water with acombination of direct and out-of-contact heat exchange, wherein the cookin stage 2 has reduced thermal demand and/or using the power systemwaste heat to directly dry co-products of the distillery stillage instage 7.

The example of FIG. 4 like FIG. 1 and FIG. 2 shows the distribution ofthe heat from the combined heat and power system used to producemechanical and electrical energy to drive the mechanical vaporcompression in stage 5, wherein the thermal energy of the distillationis greatly reduced and the electrical energy may be less than or equalto the amount needed to drive the compressor of the vapor compressionsystem, leaving little or no residual electrical to serve the electricaldemand of the other stages which require mechanical energy such aspumping, stirring as in the cooking in stage 2, and fermentation instage 4. FIG. 4 shows the heat from the combined heat and power systemused to generate steam by heat recovery with steam generation, whereinthe steam is then passed through a steam turbine which generateselectricity with the low pressure stage of the turbine passing theexhaust steam on to potentially all other thermally intensive stages,such as the cook in stage 2, the distillation in stage 5 (for any steamnot offset by the mechanical vapor compression), and the dehydration instage 8, and the steam turbine electrical power is used to meet theelectrical power demand of the other stages which require mechanicalenergy such as pumping, stirring as in the cooking in stage 2, andfermentation in stage 4.

The examples of FIG. 5 and FIG. 6, like FIGS. 1, 2, 3, and 4, show thedistribution of the heat from the combined heat and power system used toproduce mechanical and electrical energy to drive the mechanical vaporcompression in stage 5 and stage 7, wherein the thermal energy ofdistillation and evaporation are greatly reduced and the electricalenergy generated may be less than or equal to the amount needed to drivethe compressor of the vapor compression system, leaving little or noresidual electrical to serve the electrical demand of the other stageswhich require mechanical energy such as pumping, stirring as in thecooking in stage 2, and fermentation in stage 4. FIG. 5 shows thedistillation in stage 5 by compression passes the heat of distillationon to a multi-effect evaporation in stage 7 for the concentration of thethin stillage bottoms from stage 5, and the cascaded steam from thefinal evaporation effect is part of the mechanical vapor compressionthat recycles the steam back to distillation stage 5. The waste heatfrom the combined heat and power is distributed to meet the thermaldemands of a cook process stage 2, distillation stage 5, and dehydrationstage 8.

The example of FIG. 7, like FIGS. 1, 2, 3 and 4, shows the distributionof the heat from the combined heat and power system used to producemechanical and electrical energy to drive the mechanical vaporcompression in stage 5 and stage 7, wherein the thermal energy ofdistillation and evaporation is greatly reduced and the electricalenergy generated may be less than or equal to the amount needed to drivethe compressor of the vapor compression system, leaving little or noresidual electrical to serve the electrical demand of the other stageswhich require mechanical energy such as pumping, stirring as in thecooking in stage 2, and fermentation in stage 4. FIG. 7 shows thedistillation in stage 5 by compression passes the heat of distillationon to a multi-effect evaporation in stage 7 for the concentration of thethin stillage bottoms from stage 5, and the cascaded steam fromreboiler-evaporator together with the final evaporation effect is partof the mechanical vapor compression that recycles the steam back todrive the distillation stage 5. The waste heat from the combined heatand power is distributed to meet the thermal demands of a cook processstage 2, distillation stage 5, and dehydration stage 8.

The example of FIG. 8, like FIGS. 1, 2, 3, and 4 shows the distributionof the heat from the combined heat and power system used to producemechanical and electrical energy to drive the mechanical vaporcompression in stage 5 and stage 7, wherein the thermal energy ofdistillation and evaporation is greatly reduced and the electricalenergy generated may be less than or equal to the amount needed to drivethe compressor of the vapor compression system, leaving little or noresidual electrical energy to serve the electrical demand of the otherstages which require mechanical energy such as pumping, stirring as inthe cooking in stage 2, and fermentation in stage 4. FIG. 8 shows thedistillation in stage 5 by compression passes the heat of distillationon to a multi-effect evaporation in stage 7 which is comprised of twoseparate reboilers, with the concentration of the thin stillage bottomsfrom the aqueous distillation tower of stage 5, and the cascaded steamfrom reboiler-evaporator together with the final evaporation effect ispart of the mechanical vapor compression that recycles the steam back todrive the aqueous distillation tower of stage 5 and biochemical bottomproduct cascaded vapors from the organic reboiler to the organicdistillation tower. The waste heat from the combined heat and power isdistributed to meet the thermal demands of a cook process stage 2, anddistillation stage 5.

The example of FIG. 9, like FIGS. 1, 2, 3, and 4 shows the distributionof the heat from the combined heat and power system used to producemechanical and electrical energy to drive the mechanical vaporcompression in stage 5, stage 7 and stage 8, wherein the thermal energyof distillation, evaporation, and dehydration is greatly reduced and theelectrical energy generated may be less than or equal to the amountneeded to drive the compressor of the vapor compression system, leavinglittle or no residual electrical energy to serve the electrical demandof the other stages which require mechanical energy such as pumping,stirring as in the cooking in stage 2, and fermentation in stage 4. Thewaste heat from the combined heat and power is distributed to meet thethermal demands of a cook process stage 2, distillation stage 5, anddehydration stage 8.

In should be noted that regarding FIGS. 1 to 9, specific unit operationsmay be omitted in some embodiments, and in these or other embodiments,other unit operations not explicitly shown may be included.Additionally, multiple pieces of equipment, either in series or inparallel, may be utilized for any unit operations, pumps, etc. Also,solid, liquid, and gas streams produced or existing within the processmay be independently recycled, passed to subsequent steps, orremoved/purged from the process at any point.

As will be appreciated by a person of ordinary skill in the art, theprinciples of this disclosure may be applied to many biorefineryconfigurations beyond those explicitly disclosed or described in thedrawings hereto. Various combinations are possible, and selectedembodiments from some variations may be utilized or adapted to arrive atadditional variations that do not necessarily include all featuresdisclosed herein. In particular, while some embodiments are directed toethanol as the primary biofuel/biochemical, the present invention is byno means limited to ethanol.

For example, the invention may be applied to ABE fermentation, producinga mixture of acetone, n-butanol, and ethanol. One or more additionaldistillation or other separation units may be included, to separatecomponents of a fermentation mixture. Also, in some embodiments, theprimary product is less volatile than water (at atmospheric pressure),rather than more volatile, as is the case with ethanol. An example of abiofuel/biochemical less volatile than water is isobutanol.

The present invention provides a biofuel or biochemical product producedby a process comprising a method of modifying a distillery orbiorefinery, wherein the distillery or biorefinery converts biomass intothe biofuel or biochemical, and wherein the biofuel or biochemical ispurified by distillation, the method comprising:

(i) introducing a mechanical vapor recompression (MVR) unit to recoverheat of the distillation, evaporation, and/or dehydration, and provide areduction in process thermal energy usage in the distillery orbiorefinery; and

(ii) introducing a combined heat and power (CHP) system having a CHPengine, to provide mechanical and electrical energy for driving the MVRunit, wherein residual waste heat of the CHP engine offsets the processthermal energy usage in the distillery or biorefinery, in conjunctionwith the MVR unit; and wherein integration of the MVR unit with the CHPsystem is balanced to optimize process energy requirements, processcarbon intensity, and/or process energy costs.

These and other combinations of heat and power optimization areavailable by the mixed combination of mechanical vapor compressionintegrated together with combined heat and power. The integration ofthese two complementary technologies, wherein the mechanical vaporcompression in distillation, evaporation, and optionally dehydrationreduces the total thermal energy demand of the distillery, and a portionof the saved thermal energy fuel is then dedicated to combined heat andpower to offset process electrical energy, allows for a simultaneousreduction in the thermal energy demand and electrical energy demand,together with a reduction in process energy costs and reduced carbonintensity for the plant.

Some variations of the invention provide a method for optimizing energyusage, production economics, and environmental performance in modifyingexisting distillation systems. The operational capabilities of adistillation system are maintained while a more energy-efficient processis added that diverts some portion of the distilled vapors, which wouldotherwise be condensed, and compresses them, heating them and raisingtheir boiling point. The compressed vapors are condensed in a reboiler,capturing the energy released that would otherwise be lost to coolingwater flowing through a condenser. The method used to drive thecompressor, the design of the reboiler, and generation of additionalusable energy are balanced to provide fully redundant capabilities withrespect to the existing system and the desired optimization.

In one aspect, a method is provided for the modification andaugmentation of a distillery wherein the addition of the discloseddistillation methods for heat management by mechanical vapor compressionwhich recovers the heat of distillation, provides a reduction in processthermal energy together with combined heat and power for the addition ofmechanical and electrical energy for driving the mechanical compression,wherein the residual waste heat of the engine offsets thermal energyrequired in the distillery in conjunction with the mechanical vaporcompression in distillation. The integration of the mechanical vaporcompression with combined heat and power is balanced to optimize thereduction in process energy requirements, process carbon intensityand/or process energy costs.

In some embodiments, the mechanical vapor compression is sized oroperated to reduce the thermal energy required in distillation inconcert with the standard steam generator that is operated at a reducedrate as a result of the reduction in steam energy demand due to energyrecovered by the mechanical vapor compression in distillation. In theseor other embodiments, the combined heat and power system is sized oroperated in concert with the mechanical demand of the mechanical vaporcompression and the thermal energy demand of the distillery wherein partof, some of, or all of the thermal energy is provided by the waste heatrecovered by the combined heat and power system.

The combination of mechanical vapor compression in distillation andcombined heat and power allows balancing of use in the distillery basedon the market price of process fuel energy and electrical energy unitprice, wherein the total process energy is not minimized, though theprocess energy costs are minimized based on the relative pricing of thetwo energy sources.

Also, the combination of mechanical vapor compression in distillationand combined heat and power allows minimization of the carbon intensityof the process through selective usage of electricity and thermal fuelin a manner that minimizes the total carbon intensity of the processenergy, though the process energy costs are not minimized because of therelative pricing of the two energy sources and the individual carbonintensities allocated to the thermal and electrical process energylifecycles.

By recapturing and recycling process heat, the disclosed technologyprovides an option for expanding biofuels/biochemical production that:

(a) reduces or eliminates the need for additional steam-generatingcapacity;

(b) reduces or eliminates the need for additional cooling capacity; and

(c) reduces or eliminates seasonal production restrictions due tocooling system capacity limitations during high ambient temperatures andhumidity.

In addition, the disclosed technology can permit production increaseswithout exceeding allowable air emissions and water usage and dischargerestrictions under existing environmental permits.

Some embodiments of the invention provide a system or sub-systemcomprising or consisting of the process or apparatus configurationdepicted as “Compound MVR-CHP Section II” in any one of FIGS. 1 to 9.Some embodiments of the invention provide instructions to retrofit anexisting distillery or biorefinery with the process or apparatusconfiguration depicted as “Compound MVR-CHP Section II” in any one ofFIGS. 1 to 9, or any other disclosure set forth herein.

The throughput, or process capacity, may vary widely from smalllaboratory-scale units to full commercial-scale biorefineries, includingany pilot, demonstration, or semi-commercial scale. In variousembodiments, the process capacity is at least about 1 kg/day, 10 kg/day,100 kg/day, 1 ton/day (all tons are metric tons), 10 tons/day, 100tons/day, 500 tons/day, 1000 tons/day, 2000 tons/day, 3000 tons/day,4000 tons/day, or higher.

All publications, patents, and patent applications cited in thisspecification are incorporated herein by reference in their entirety asif each publication, patent, or patent application was specifically andindividually put forth herein.

In this detailed description, reference has been made to multipleembodiments of the invention and non-limiting examples and drawingsrelating to how the invention can be understood and practiced. Otherembodiments that do not provide all of the features and advantages setforth herein may be utilized, without departing from the spirit andscope of the present invention. This invention incorporates routineexperimentation and optimization of the methods and systems describedherein. Such modifications and variations are considered to be withinthe scope of the invention defined by the claims.

Where methods and steps described above indicate certain eventsoccurring in certain order, those of ordinary skill in the art willrecognize that the ordering of certain steps may be modified and thatsuch modifications are in accordance with the variations of theinvention. Additionally, certain of the steps may be performedconcurrently in a parallel process when possible, as well as performedsequentially.

Therefore, to the extent that there are variations of the invention,which are within the spirit of the disclosure or equivalent to theinventions found in the appended claims, it is the intent that thispatent will cover those variations as well. The present invention shallonly be limited by what is claimed.

REFERENCES

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What is claimed is:
 1. A method of modifying a distillery orbiorefinery, wherein said distillery or biorefinery converts biomassinto a biofuel or biochemical, and wherein said biofuel or biochemicalis purified by distillation, said method comprising: (i) introducing amechanical vapor recompression (MVR) unit to recover heat of saiddistillation, wherein said MVR unit is integrated within said distilleryor biorefinery to provide a reduction in process thermal energy usage insaid distillery or biorefinery, wherein said MVR unit comprises multiplecompressors and/or multiple compressor stages, and wherein cascaded heatfrom said distillation is integrated with multiple distillery orbiorefinery process stages, including at least one distillery orbiorefinery process stage that is not distillation; (ii) providingmechanical and electrical energy for driving said MVR unit; and (iii)balancing process energy requirements, process carbon intensity, and/orprocess energy costs through integration of said MVR unit within saidmultiple distillery or biorefinery process stages.
 2. The method ofclaim 1, wherein cascaded heat from said distillation is integrated withmultiple stillage evaporations, and wherein compressed biofuel orbiochemical vapors and/or steam generated in at least one stillageevaporator is compressed and returned to said distillation.
 3. Themethod of claim 1, wherein cascaded heat from said distillation isintegrated with vapor-phase dehydration, and wherein compressed biofuelor biochemical vapors as anhydrous vapors and/or steam generated in atleast one stillage evaporator is compressed and returned to saiddistillation.
 4. The method of claim 1, wherein cascaded heat from saiddistillation is integrated with multiple stillage evaporations includinga first evaporator, wherein compressed steam from said first evaporatoris optionally split between said distillation and a second evaporator,and wherein said distillation and at least one of said first and secondevaporators are operated at equal pressure, thereby allowing acompressor stage to cascade heat of evaporation between saiddistillation and said multiple stillage evaporations.
 5. The method ofclaim 1, wherein cascaded heat from multiple stillage evaporations tosaid distillation is integrated with compression of steam from at leastone reboiler-evaporator to drive said distillation and evaporation,wherein said distillation and said evaporation are operated such thatevaporation pressure is higher than distillation pressure, therebyallowing compressor stages to cascade heat of evaporation into saiddistillation.
 6. The method of claim 1, wherein said MVR unit is sizedor operated with a standard steam generator to reduce thermal energyrequired in said distillation, and wherein said standard steam generatoris operated at a reduced rate as a result of reduction in steam energydemand due to energy recovered by said MVR unit.
 7. The method of claim1, said method further comprising introducing a combined heat and power(CHP) system having a CHP engine, to provide said mechanical andelectrical energy for driving said MVR unit, wherein residual waste heatof said CHP engine offsets said process thermal energy usage in saiddistillery or biorefinery, in conjunction with said MVR unit.
 8. Themethod of claim 7, wherein said CHP engine is sized or operatedaccording to the mechanical demand of said MVR unit and thermal energydemand of said distillery or biorefinery, wherein at least some of saidthermal energy demand of said distillery or biorefinery is provided bywaste heat recovered by said CHP system.
 9. A distillery or biorefineryprocess comprising the method of claim
 1. 10. The distillery orbiorefinery process of claim 9, wherein said biofuel or biochemical isselected from the group consisting of methanol, ethanol, 1-propanol,2-propanol, n-butanol, isobutanol, 2-butanol, tert-butanol, acetone, andcombinations thereof.
 11. A system configured for a distillery orbiorefinery, wherein said distillery or biorefinery is capable ofconverting biomass into a biofuel or biochemical, and wherein saiddistillery or biorefinery includes distillation configured to purifysaid biofuel or biochemical, said system comprising: (i) a mechanicalvapor recompression (MVR) sub-system configured to recover heat of saiddistillation and provide a reduction in process thermal energy usage insaid distillery or biorefinery, wherein said MVR sub-system comprisesmultiple compressors and/or multiple compressor stages, and whereincascaded heat from said distillation is integrated with multipledistillery or biorefinery process stages, including at least onedistillery or biorefinery process stage that is not distillation; and(ii) a power sub-system configured to provide mechanical and electricalenergy for driving said MVR sub-system, wherein said MVR sub-system andsaid power sub-system are integrated and configured to offset saidprocess thermal energy usage in said distillery or biorefinery.
 12. Thesystem of claim 11, wherein vapor from said distillation cascades heatto multiple stillage evaporators, biofuel or biochemical vapors and/orsteam generated in at least one stillage evaporator is compressed andreturned to said distillation within said distillery or biorefinery. 13.The system of claim 11, wherein said multiple compressors and/ormultiple compressor stages are configured to cascade heat of evaporationbetween said distillation and multiple stillage evaporations, whereinvapor from said distillation provides heat to a first stillageevaporator, and wherein steam generated in said first stillageevaporator is compressed and compressed steam is optionally splitbetween said distillation and a second stillage evaporator.
 14. Thesystem of claim 11, wherein said multiple compressors and/or multiplecompressor stages are configured to cascade heat of evaporation frommultiple stillage evaporators into said distillation, and wherein steamfrom at least one stillage evaporator is compressed and returned to saiddistillation and fed to at least one stillage evaporator to driveevaporation.
 15. The system of claim 11, wherein said MVR sub-system isconfigured with a standard steam generator to reduce thermal energyrequired in said distillation.
 16. The system of claim 11, wherein saidbiofuel or biochemical is selected from the group consisting ofmethanol, ethanol, 1-propanol, 2-propanol, n-butanol, isobutanol,2-butanol, tert-butanol, acetone, and combinations thereof.
 17. Thesystem of claim 11, wherein said system is a retrofit to an existingplant.
 18. The system of claim 11, wherein said distillery orbiorefinery is a greenfield plant.